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Two Charge (2) Dicorotron System on a Docutech/6135

By Raymond Cote 

I have been asked by a number of technicians if a two Charge dicorotron system is better than the standard 3-dicorotron system. And the answer is always the same: Personally I could not really tell the difference in copy quality between the two systems.  This argument has been going on for many years since Xerox tried to eliminate the zero (0) dicorotron wire in the 6135 printer. At the time, one of the official reasons was that it would eliminate one dicorotron and will eventually save the company many dollars in parts cost over the life of this product since the third dicorotron is not really necessary. I always had trouble with that theory because Xerox had parts manufactured to their (very) specific specifications and at a very low cost to them. Eliminating one dicorotron assembly might, over a long period of time, save the company some money but was the savings worth the effort?  

However back on the ranch, as a field service engineer servicing this family of copiers we had second thoughts about modifying them in the field. Shortly after the decision to modify the three-dicorotron system, manufacturing started to release new 6135’s already modified.   The decision was already made and we had to live with it. In the long run it was hard to tell if there was any real difference between the three-dicorotron system and the two-dicorotron system. The argument for and against it went on till the time I retired from Xerox in 2000.     

Technicians that talked about this were usually in agreement that it is in your best interest to do nothing and modify nothing connected with the three dicorotron system. If it works, leave it alone. However if you are hell bent on modifying the system then use the factory authorized retrofit kit, part number 600K71930. If the kit is not available then follow these instructions very carefully and hope that the Greek god of electric writing will be kind to you. 

Caution: before working on any printer or copier, please power down the printer and remove the power cord from the wall. Open both front doors and remove all associated panels so that you will have full access to the Charge area. It is also recommended that you remove the top cover, laser assembly and the toner bottle. Cover the photoreceptor belt with an 11” x 17” sheet of 20-pound paper to protect the photoreceptor. Check the photoreceptor belt ground bush and segment lamps for total operation and zone rollers for ease of rolling and no contamination.  

Remove all three Charge Dicorotrons. Replace the zero (0) Dicorotron with a yellow dicorotron (125K1450). Then remove the Dicorotron wire assembly (48K56790) from the housing and install the Shield (55K310). Slide the dicorotron assembly into the Charge Zero (0) position. Replace Charge 1 and Charge 2 Dicorotrons with yellow (chopped) Dicorotrons 125K1450 and make sure they are 2.9mm above the photoreceptor belt (1R88) and balanced front to back. The height adjustment is critical and must be done with care. The best way to make this adjustment is to remove the laser assembly, thereby giving you greater access to the Charge bracket assembly.  Also be aware that the adjustment in the service manual (ADJ 9.6) should be consulted for the actual adjustment procedure. But you should be aware that the information in the adjustment procedure would reflect the height adjustment using both types of dicorotrons. Be careful here because the yellow dicorotrons are shorter than the white ones and that’s the reason they call the yellow ones “chopped dicorotrons”.  

While you are in the belt cavity, it will be a good time to check the ESV height adjustment (ADJ 9.5). Remove the toner bottle assembly from the toner dispenser and perform the adjustment. 

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